Heat activated adhesive

ABSTRACT

The present invention provides thermally activated adhesive compositions comprising polymer and polyester wherein the adhesive polymer comprises a polymer having hydroxyl and phenyl groups and adhesive films made from the adhesive compositions.

The present invention relates to thermally activated adhesivecompositions that form adhesive films wherein the surface practicallydoes not have adhesive properties and adhesive films made from saidadhesive compositions.

Adhesives that have as their main component an adhesive polymer, alsocalled pressure sensitive adhesive (adhesive agent), and it is amaterial where only by the application of pressure it is easily andstrongly adhered. However, because of the fact that it has adhesiveproperties, the processing properties for punching processing etc., arepoor and also the positioning is difficult.

Then, there have been numerous technologies for the control of theadhesive properties of the adhesive films (that have a binding layerthat is formed from an adhesive agent). For example, there is the methodwhere onto the adhesive surface, by using an embossing technologicalprocess indentations and protrusions are provided and the apparentadhesive properties are reduced, and then by heating these are smoothedout and flattened and by that the adhesive force is increased (disclosedaccording to the reported in the Japanese Patent Application Laid OpenNumber Hei-Sei 4-309583). Namely, it is a method where at the time ofthe processing and positioning, the state of protrusions andindentations of the adhesive surface, that has a low adhesive forcerelative to the material that is the subject of the adhesion, ismaintained, and at the state where the adhesion is to be completed, theadhesive surface is smoothed out and flattened and the adhesive force isincreased.

Also, as an adhesive film that has an adhesive layer containing acrystalline component, there is a material that has been disclosedaccording to the reported in PCT Publication WO 97/46633. By theadhesive layer of this adhesive film inside the adhesive polymermaterial a crystalline acrylate component is incorporated as acontinuous phase. Also, by this adhesive layer, it is relativelydifficult to lose the adhesive force and to completely lose the adhesiveproperties and usually, the binding surface (the adhesive surface) hasadhesive properties. Consequently, properties of memory of its shape aregenerated and the adhesive surface that has protrusions and indentationsas the secondary shape, is changed to the smooth adhesive surface whichis the memory shape state (the primary state), and by that the same wayas in the above described the easiness of the processing properties andthe positioning properties, is increased.

However, in the case of such adhesive films, after the stage of theprocessing and the positioning (initial stages) it is not possible toform a smooth binding surface possessing film adhesive. In the case whenthe binding surface has adhesive properties and not only that but alsoit has a structure containing protrusions and indentations, theelimination of the impurities that are adhered at the time of theprocessing and positioning, is difficult. Also, in order to reliablysustain such binding surface with protrusions and indentations, it isnecessary to have a specific liner (a material where the release surfacealso has a structure containing protrusions and indentations, etc.), andthe economics are also complicated. Also, the Tg of the adhesive polymermaterial itself is relatively low, and the thermal resistance propertiesare also low.

On the other hand, adhesives are also known where adhesive propertiesare generated or increased by heating, and they are so-called thermallyactivated adhesive. In the case of the thermally activated adhesive, itis also called hot melt film adhesive, or heat sensitive type adhesive.Also, in order to increase its binding strength, the material is alsoknown where an adhesive polymer material and a thermoplastic resinmaterial are combined.

Regarding the thermoplastic resin materials that are used as thermallyactivated adhesive, there are many types, for example, it is possible touse polyester material. For example, in the reported in the descriptionof the Japanese Patent Application Laid Open Number Showa 56-501131,thermally activated adhesive composition material with improved thermalresistance properties, has been disclosed. Namely, it is a adhesivecomposition material that contains (i) approximately 100 weight parts ofa thermoplastic polymer material, (ii) a cross-adhesive (crosslinkingagent), and (iii) approximately from 1 to 100 weight parts of an organicpolymer material that has a complex number of functional radicals thatcan be used for the crosslinking reaction with the above describedcrosslinking agent. As the above described thermoplastic polymermaterial, it is possible to use polyester or polyurethane etc., and asthe above described organic polymer material, it is possible to usepolyalcohol type or polyamine type polymers, etc. Also, as the abovedescribed crosslinking agent, it is possible to use diisocyanate orpolyisocyanates. In the case of such crosslinked thermally activatedadhesive composition materials, it is possible to efficiently increasethe thermal resistance properties. Also, in the case of such thermallyactivated adhesives, usually, they do not have adhesive properties atroom temperature, and because of that it is also possible: to increasethe ease of processing and positioning properties. However, in thisdisclosed adhesive composition material, an adhesive polymer is notcontained and because of that it is difficult to increase the bindingstrength.

On the other hand, in the description reported according to the JapanesePatent Application Laid Open Number Hei-Sei 8-134428, a hot meltadhesive composition material is disclosed that contains a thermoplasticadhesive, and an adhesive polymer. In this patent report, as thethermoplastic adhesive polyester, and as the adhesive polymer materialisooctyl acrylate—acrylic acid type copolymer material, arecorrespondingly given as the examples. In the case of this compositionmaterial also it is necessary that there is a phase separation of theadhesive polymer material and the thermoplastic adhesive. The reason forthat is so that the coating properties of the hot melt adhesive agent atthe time when it is coated in a liquid state, are increased, and also,so that the adhesive properties are maintained for a relatively longperiod of time (even when after cooling it is apparently solidified)after the coating technological process. Namely, in the case of thiscomposition material, it is a material that is more appropriate to beused as a adhesive of the type that is liquefied and then used, than thematerial used as a film adhesive, where by heating the adhesiveproperties of the binding surface are increased.

In the descriptions reported according to the Japanese PatentApplication Laid Open Number Hei-Sei 6-256746, Japanese PatentApplication Laid Open Number Hei-Sei 5-339556, a thermally activatedfilm adhesive has been disclosed that is formed from a compositionmaterial, where as the thermoplastic resin material a phenoxy resin, andthen an epoxy resin, and their crosslinking agents are contained. In thecase of the above described adhesive acrylic type polymer material, itis preferred that it is a material that contains in its molecule acarboxyl radical, a hydroxyl radical, or an epoxy radical.

Usually, the adhesives in the form of films that are usable inelectrical type applications, are used so that after the punching, theyare positioned and the electronic part etc., is bonded, and because ofthat it is good if the adhesive properties (the adhesive properties atroom temperature, at approximately 25° C.) are as low as possible, andthe materials that practically do not have adhesive properties areespecially appropriate. Also, regarding the adhesives for electricalapplications, there are many cases where thermal resistance propertiesare required and because of that usually, the pressure sensitiveadhesive agents are not appropriate for these types of applications.

On the other hand, in the case of the combination of the usual adhesivepolymer material and the thermoplastic resin material, the bondingsurface of the film adhesive was not prevented from having adhesiveproperties. And in the case of film adhesive where the bonding surfacehas adhesive properties, it is not possible to solve the problemsassociated with the previously described adhesive film. Also, if anadhesive polymer material is not efficiently used it is difficult toincrease the adhesive force.

Consequently, the goal of the present invention is to provide athermally activated adhesive composition material whereby it is possibleto form an adhesive in the form of a film where the surface practicallydoes not possess pressure sensitive adhesive properties (in other words,it is “tack-free”), and the problems associated with the previouslydescribed adhesive film can be solved, and also, where it is easy toincrease the bonding force.

The present invention, in order to solve the above described problems,provides a thermally activated adhesive composition material,characterized by the fact that it is a thermally activated adhesivecomposition material that is formed from an adhesive polymer, and apolyester, where the above described adhesive polymer material containsin its molecule hydroxyl and phenyl radicals or groups. The inventionalso provides adhesive films comprising said adhesive composition.

According to the thermally activated adhesive of the present invention,it has as its characteristic the fact. that the adhesive polymer that isused for compounding with the polyester material, is formed so that itcontains in its molecule hydroxyl and phenyl radicals. In the case ofsuch adhesive polymer material, the compatibility properties with thepolyester are high, and it is a material where the adhesive propertiesof the adhesive composition material at room temperature, can bepractically eliminated, and compared to the usual pressure sensitiveadhesive, it has high thermal resistance properties. On the other hand,because at the time when it is heated, it shows high adhesiveproperties, it is a material whereby a thermal pressure adhesionoperation, it is possible to have bonding of the materials subjected tothe bonding, to each other, at a high adhesive strength.

Regarding the proportion of the above described polyester that iscontained in the total of the adhesive composition material, usually, itis in the range of 5-50 weight %, and preferably, it is in the range of10-45 weight %. If the amount of the polyester material is too small, itis not possible to practically eliminate the room temperature adhesiveproperties of the adhesive composition material, and on the contrary, ifthat contained amount is too large, there is the risk that a highadhesive strength immediately after the pressure adhesion is notobtained. On the other hand, regarding the proportion contained of theabove described adhesive polymer material containing two functionalradicals (a hydroxyl radical and a phenyl radical) in the totalcomposition of the adhesive material, usually it is in the range of50-95 or more weight %, and preferably, it is in the range of 55-89weight %.

Regarding the above described polyester, as long as it is a materialthat at room temperature (approximately 25° C.) it is practicallynon-adhesive, and also, that has crystalline properties and can bemelted upon heating, there are no particular limitations. However,polycaprolactone is preferred. The polycaprolactone is (i) a polyesterthat is obtained by the polymerization of caprolactone containingstarting material, or (ii) it is a polyester where the polymer unitobtained by the caprolactone open ring polymerization (unit), iscontained in the molecule. In the case of the composition material thatcontains the above described adhesive polymer and polycaprolactone, itis a material where because of the crystallization of thepolycaprolactone, at room temperature it almost has no adhesiveproperties, however, by heating, the polycaprolactone is melted andstrong bonding strength appears. Such effect is especially increased inthe case when the adhesive polymer material that contains in itsmolecule at the same time a hydroxyl radical and a phenyl radical, is anacrylic type polymer material. This is because of the fact that thecompatibility properties between such acrylic type polymer material andpolycaprolactone, are especially excellent.

The thermally activated adhesive composition according to the presentinvention preferably contains a crosslinking agent. By that it is amaterial where the thermal resistance properties that are required fromthe adhesives used in electrical type applications, and especially, thesolder resistance thermal properties, can be effectively increased.

The thermally activated adhesive composition material according to thepresent invention can be also used as a type of adhesive that is used asit is liquefied by heating, however, it is preferred that it isadvantageously used as a film adhesive where the adhesive properties ofthe bonding surface are increased by heating. Namely, regarding thefirst practical implementation of the present invention, a film adhesiveis suggested that is formed from the above described thermally activatedadhesive composition material and that has the desired thickness. Byusing such film adhesive, it is possible that at room temperature theadhesive properties are practically eliminated, and compared to theusual pressure sensitive adhesive, it is a material that has highthermal resistance properties. On the other hand, at the time of theheating, it shows high adhesive properties and because of that it is amaterial whereby because of the high bonding force developed through athermal and pressure adhesion operation the materials subject to theadhesion can be bonded to each other.

Regarding the adhesive polymer material used according to the presentinvention, as long as it is a polymer material, that shows adhesiveproperties at room temperature (approximately 25° C.), and that isformed so that it contains a polymer that has in its molecule a hydroxylradical and a phenyl radical, there are no particular limitations. Forexample, it is possible to use acrylic type polymers, nitrile -butadiene type copolymer materials (NBR, etc.), styrene - butadiene typecopolymers (SBR, etc.), polyurethanes, silicone type polymers, etc.Regarding the adhesive polymer material, it is possible to use one typeof these polymer materials individually, and it is also possible thatthe structure is formed from a mixed material containing 2 or more typesof these materials.

Regarding the polymer material that contains in its molecule the abovedescribed functional radicals, it is a material that is obtained bypolymerization using as the starting monomers, raw materials thatcontain monomer possessing in its molecule a hydroxyl radical andmonomers possessing in its molecule phenyl radical. Or, it is also agood option if after the polymerization, different functional radicalsthat are contained in the molecule (for example, carboxyl radicals) arereacted and they are changed to a hydroxyl radical and phenyl radical.

Here, one example of the preferred acrylic type polymer that can be usedaccording to the present invention, will be described. It is a materialwhere as the starting monomer material, the raw materials including (A)1 or 2 and more phenoxy alkyl acrylates, (B) monomers containing intheir molecule a hydroxyl radical, and depending on the requirements (C)(meth)acrylic acid alkyl ester, are copolymerized according to the usualmethods like for example, emulsion polymerization, solutionpolymerization, agglomeration polymerization, suspension polymerization,etc., and the material is manufactured.

As the above described component (A), for example, phenoxy ethylacrylate, phenoxy propyl acrylate, etc., can be used. Also, as the abovedescribed component (B), for example, 2-hydroxyethyl acrylate,2-hydroxypropyl acrylate, 2-hydroxymethyl acrylate, 2-hydroxyethylmethacrylate, 2-hydroxypropyl methacrylate,hydroxy-3-phenoxypropylacrylate etc., can be used. Then, as the abovedescribed component (C), for example, it is possible to use n-butylacrylate, isobutyl acrylate, isooctyl acrylate, 2-ethyl hexyl acrylate,etc.

As the above described component (B), hydroxy-3-phenoxypropyl acrylateetc., materials are preferred, that are monomers where in the moleculeboth a hydroxyl radical and a phenyl radical, are contained. By that, itis possible to especially efficiently increase the compatibilityproperties of the adhesive polymer material relative to the polyestermaterial.

Regarding the proportion (weight ratio) of the monomer unit, thatcontains the above described two functional radicals, contained in thepolymer units of the total material of the adhesive polymer (namely,total monomer units derived from the component (A) and component (B))usually it is 70 weight % and above, preferably it is 80 weight % andabove, and especially preferably, it is 90 weight % and above. If theamount contained of the above described monomer units containing the twofunctional radicals is too low, there is the risk that the compatibilityproperties relative to the polyester material are also decreased. Also,regarding the proportion of monomer units derived from the component(B), that is contained in the polymer units of the total polymermaterial, it is 0.5 mole % and above, preferably, it is 1 mole % andabove, and especially preferably, it is in the range of 5-15 mole %. Ifthe amount contained of the monomers derived from the component (B) istoo low, there is the risk that it would be ineffective in thegeneration of sufficiently high adhesive force (for example, 0.5 kg/cmand above) immediately after the pressure adhesion. And if the amountcontained of the units derived from the component (B) is too high, thereis the risk that the compatibility properties relative to the polyestermaterial would be decreased.

Regarding the adhesive polymer material that is used according to thepresent invention, as long as the results from the present invention arenot hindered, in addition to the above described polymer materialcontaining the two functional radicals (the hydroxyl radical and thephenyl radical), it is also possible that polymer material that does notcontain the above described two functional radicals, is also contained.However, the proportion in the total adhesive polymer material, of theabove described two functional radicals (hydroxyl radical and phenylradical) containing polymer is usually 70 weight % and above,preferably, it is 80 weight % and higher, and especially preferably, itis 90 weight % and higher.

Also, regarding the molecular weight of the adhesive polymer material,it is good as long as it is within the range where the desired adhesivestrength is generated, and usually, the weight average molecular weightis in the range of 10,000-100,000. Also, the same way as in the case ofthe pressure sensitive adhesive according to the previous technology,together with the adhesive polymer material, it is also possible to usean adhesion imparting agent. Also, as long as it is within the rangewhere the results from the present invention are not hindered, it isalso a good option if the above described adhesive polymer is a materialthat is crosslinkable by using heat or a radiation beam (ultra-violetbeam, electron beam, etc.). The crosslinking of the adhesive polymermaterial can be done as a crosslinking prior to or after the bonding tothe material that is the subject of the adhesion.

On the other hand, regarding the molecular weight of the polyestermaterial, it is a good option as long as it is within the range wherethe predetermined adhesive strength is generated, and also, as long asthe composition material practically does not have adhesive propertiesat room temperature. And expressed as a weight average molecular weight,it is usually in the range of 500-200,000, and preferably, it is withinthe range of 1,000-100,000. In the case when the molecular weight is toolow, there is the danger that the adhesive force would be decreased, andon the contrary, in the case when it is too high, the compatibilityproperties relative to the adhesive polymer material are decreased, andthere is the danger that the elimination of the adhesive properties ofthe composition material at room temperature would become difficult.

Regarding the thermally activated adhesive composition materialaccording to the present invention, it can be manufactured as throughthe usual mixing operations, all the raw materials are homogeneouslymixed and combined. For example, adhesive polymer material, polyester,solvent agent, crosslinking agent added depending on the requirements,etc., additives, are mixed and combined by using a mixing equipment likea Homomixer, a planetary mixer, etc., and each of the materials ishomogeneously dissolved or dispersed, and by that it is possible toprepare the liquid state composition material.

Regarding this liquid state composition material, usually, it can beprepared as the first solution where the above described adhesivepolymer material is liquefied, and the second solution where the abovedescribed crystalline polymer is liquefied, are mixed and combined, andthe above described adhesive polymer material and it is prepared as theabove precursor solution where the above described crystalline polymermaterial, are homogeneously liquefied, and then this precursor solutionis dried, and then the thermally activated adhesive composition materialis formed from the dried material obtained from this precursor solution.If this is done, it is possible to form a specific morphology from thecrystalline polycaprolactone and the adhesive polymer material thatcontains a hydroxyl radical and a phenyl radical (mutually continuousstructure) and it is possible to especially efficiently demonstrate theabove described properties (non-adhesive properties at room temperatureand high adhesive strength). Moreover, in the case when a crosslinkingagent is added, usually, a third solution containing the crosslinkingagent is added to the above described precursor liquid material.

The liquid composition material that has been manufactured according tothe above described is coated on the substrate material and dried, andby that the film adhesive from the above described adhesive compositionmaterial, can be formed. As the coating measures, it is possible to usea knife coater, a roll coater, a die coater a bar coater, etc., wellknown measures. As the above described substrate material, it ispossible to use a material that is a release material, like a lineretc., and it is possible to use the material that must be bonded, or anadhesive sheet supporting material etc. In the case when a material thathas release properties, like a liner etc., is used, it is possible toobtain a material where the film adhesive agent that is formed from theadhesive composition material, is easily and simply removed.

Also, regarding the drying at the time of the formation of the filmadhesive, usually, it is conducted at a temperature in the range of60-180° C. And the drying period is usually in the range from severaltens of seconds to several minutes. Regarding the thickness of the. filmadhesive, it is in the range of 10-1,000 micrometers, and preferably, itis in the range of 20-500 micrometers, and especially preferably, it isin the range of 50-100 micrometers.

The film adhesive according to the present invention can also be used asthe adhesive layer of an adhesive (bonding) sheet. Namely, in the caseof the present invention an adhesive sheet is suggested, that has asupporting material and an adhesive layer that is formed from athermally activated adhesive composition material that is fixed on oneof the main surfaces of its supporting material. There are no particularlimitations regarding the above described supporting material, however,usually, the materials used as the base films in the adhesive sheetsaccording to the previous technology, are used, and such materials thathave flexible properties can be used. For example, it is possible to usepaper, metal films, plastic films etc. As the plastic films, it ispossible to use polyimide, polyvinyl chloride, acrylic type polymers,fluorinated type polymers, polyester (PET etc.), polyurethane etc.,synthetic polymer materials.

Regarding the supporting material, it is a good option if it is amaterial that is visible light and ultra-violet light permeable, and itis also a good option if it is a material that is colored or that isdecorated by printing etc.

Also, it is a good option if it is a material where in order to impartan appearance with metal gloss type of properties, it has been providedwith a metal vapor deposited layer. Then, in order to impart opticalcapability to the bonding sheet, it is also possible to use a lightpolarization film, a dielectric reflective film, a recurrent reflectionfilm, a prism film, a fluorescent light film, a film typeelectroluminescence element etc., as the supporting materials. On theother hand, in order to increase the soiling resistance properties ofthe front surface of the supporting material, it is also possible toform an optical catalyst layer on the front surface of the supportingmaterial. Also, it is a good option if the supporting material has astructure that is formed from tow or more different types of layers.Regarding the thickness of the supporting material, usually, it is inthe range of 5-500 micrometers, and preferably, it is in the range of10-300 micrometers. If the thickness is too low, the mechanical strengthof the bonding sheet is decreased, and there is the danger that thedurability properties would be decreased. And on the contrary, if thethickness is too high, the flexibility properties and the elasticproperties of the whole body of the bonding sheet are decreased, andthere is the risk that the gluing operation would become difficult.

On the surface of the side of the supporting material where the bondinglayer is to be formed it is also possible that a primer layer isprovided. Usually, the primer is prepared as a solution that containsthe material that forms the primer is prepared, and then this is coatedon one of the main surfaces of the supporting material and the primerlayer is formed.

The bonding surface of the adhesive is usually protected by a liner.This liner is usually formed from paper, plastic film, or a film that isformed as those two layers are laminated as laminated layers.

Also, in the adhesive composition according to the present invention, aslong as it is within the range where the result from the presentinvention is not hindered, it is possible to add additive agents thatare well known from the previous technology. For example, there are thefollowing: viscosity regulating agents, leveling agents, ultra-violetlight absorbing agents, anti-oxidation agents, fungus resistant agents,glass beads, etc., fine, microscopic particles, elastic fine microscopicspheres that are formed from adhesive polymer material or fromnon-adhesive rubber type polymer material, etc.

As it has been described here above, for the adhesive compositionmaterial according to the present invention it is preferred that itcontains a crosslinking agent. The crosslinking agent is a material thatcan increase the thermal resistance properties of the adhesive agentcomposition material. As the crosslinking agents, for example, it ispossible to use isocyanate compounds, melanin compounds, epoxycompounds, poly (meth)acrylate compounds, etc. regarding the proportionof the crosslinking agent that is contained in the total material of theadhesive composition, usually, it is 20 weight % or less, preferably, itis in the range of 0.2-10 weight %, and especially preferably, it is inthe range of 0.5-5 weight %. If the amount of the crosslinking agent istoo small, there is the risk that it would not be possible to increasethe thermal resistance properties, and on the contrary, if the amount ofthe crosslinking agent is too high, there is the risk that the adhesivestrength would be decreased.

Moreover, it is possible that the adhesive composition material isactivated before or/and after it is bonded to the material that is thesubject of the binding. However, in the case when the adhesivecomposition material is crosslinked prior to its appropriate use on thematerial subject to the bonding, the adhesive composition materialshould of such type that it demonstrates sufficient thermal adhesionproperties upon heating. Also, regarding the crosslinking of theadhesive composition material, usually, it is conducted as the adhesivepolymer material is crosslinked.

EXAMPLE 1

First, an ethyl acetate solution containing an adhesive polymer material(concentration of the non-volatile part =30 weight %), and a toluenesolution containing polycaprolactone (concentration of the non-volatilepart =30 weight %) are mixed, and the precursor solution was formed.This precursor solution is coated on the surface of release type film(PET film) and dried, so that on the surface of the release filmmaterial a film of adhesive is formed with a thickness of 60micrometers. In Table 1 the composition of the film adhesive is shown.Moreover, according to Examples 5-8, in the above described precursorsolution the predetermined amount of an isocyanate type crosslinkingagent is added, and the solution obtained after the addition is coated,and dried and a film adhesive was formed.

For the film adhesives obtained according to all the practical examples,it was confirmed that they do not have adhesive properties at 25° C. (bythe finger—tack test). Also, the film adhesives according to all thepractical examples, were capable of thermal activation at 120° C.

Moreover, regarding the adhesive polymers according to each practicalexample, the starting monomer material, formed from a monomer where inthe molecule a phenoxy radical is contained (phenoxy ethyl acrylate,“BISCOAT #192”, manufactured by Osaka Organic Chemistry IndustriesCompany), and a monomer that contains in its molecule a phenoxy radicaland a hydroxyl radical (2-hydroxy-3-phenoxy propyl acrylate, “ARONIXM-5700”, manufactured by Toatsu Gosei Chemical Industries Company), wassolution polymerized in an ethyl acetate solvent medium, and by that thematerial was prepared. Also, for each practical example, regarding thecontained amount of the monomer that contains in its molecule a phenoxyradical and a hydroxyl radical (M5700), was as it is shown here below.

Comparative Example 1

On the other hand, besides the fact that as the adhesive polymermaterial a material was used that did not contain in its molecule at thesame time a phenoxy radical and a hydroxyl radical, the technologicalprocedures of Example 1 were followed, and the film adhesive accordingto Comparative Example 1, was formed. The composition of the filmadhesive is shown in Table 1. The film bonding composition according toComparative Example 1 showed adhesive properties at a temperature of 25°C. (according to the finger tack test).

TABLE 1 Composition Table Example 1 PS1/PCL = 70/30 Example 2 PS2/PCL =70/30 Example 3 PS2/PCL = 85/15 Example 4 PS2/PCL = 55/45 Example 5PS2/PCL/L45 = 70/30/0.7 Example 6 PS2/PCL/L45 = 70/30/1.5 Example 7PS2/PCL/L45 = 70/30/2.3 Example 8 PS2/PCL/LA5 = 70/30/4.5 Example 9PS3/PCL = 70/30 Example 10 PS4/PCL = 70/30 Comparative Example 1 PS5/PCL= 70/30 The above described parts in all cases represent parts byweight. PCL: polycaprolactone, manufactured by Daicell Chemical Company“PURAKUCELL H7”; molecular weight = 70,000 PS1: #192: M5700 = 95:5 (moleratio) PS2: #192: M5700 = 90:10 (mole ratio) PS3: #192: M5700 = 99:1(mole ratio) PS4: #192: M5700 = 97:3 (mole ratio) PS5: 2-ethyl hexylacrylate: acrylic acid = 90:10 (weight ratio) L45: isocyanate typecrosslinking agent (“CORONATE”, manufactured by Nippon PolyurethaneCompany)

In the space between 2 polyimide films with a thickness of 25micrometers, the film adhesives according to each of the samplespresented in Table 2, were inserted and placed, and it was pressureadhered at a temperature of 120° C., at a pressure of 5 kg/cm2, for aperiod of 1 minute, and the bonding strength after the adhesion wasevaluated. The results are shown in Table 2. Moreover, the bonding forcewas measured as the peel strength that occurs at a separation speed of50 mmnnminute, in a 180 degree peel test.

TABLE 2 Adhesive Strength (after the pressure adhesion) #192/M5700[kg/cm] Adhesive Strength Example 1 95/5 0.55 Example 2  90/10 0.57Example 9 99/1 0.21 Example 10 97/3 0.43 Comparative Example 1 — >0.1

Also, from these results, it was understood that in order to obtain abonding strength that is 0.5 kg/cm or higher, after the pressureadhesion, it is appropriate that the contained amount of the monomerunit that contains a phenyl radical and a hydroxyl radical, in theadhesive polymer material, is 5 mole % or higher.

On the other hand, in the space between a 2 mm thick polyether imideplate and a 25 micron thick polyimide film, the film adhesives accordingto each of the examples shown in Table 3, are inserted and placed, andthen a pressure adhesion was conducted at a temperature of 120° C.,pressure of 5 kg/cm2, for a period of 1 minute, and after that, aheating was conducted at a temperature of 150° C. for a period of 30minutes (aging or post-cure) and the materials that have undergone thatwere evaluated for their bonding strength. The results are shown inTable 3. Also, the presence or absence of air bubbles at the time whenon the adhesive films according to each of the examples, solder materialat a temperature of 260° C. was placed for 1 minute, was monitored. Thecases where there were no air bubbles were evaluated as “pass”. The sameway, the results are shown according to the presented in Table 3.

TABLE 3 Adhesive Strength (after pressure adhesion, post cure) andsolder resistant thermal properties (260° C./1 minute). AdhesiveStrength Solder Resistant Crosslinking Agent [kg/cm] Thermal Propertiesweight parts Example 2 2.0 there are air bubbles 0 Example 3 1.3 thereare air bubbles 0 Example 4 2.0 there are air bubbles 0 Example 5 2.2pass 0.7 Example 6 2.7 pass 1.5 Example 7 1.8 pass 2.3 Example 8 1.6pass 4.5

From these results, it was understood that in order to practicallydemonstrate especially good solder resistant thermal properties (thermalresistance properties test under conditions that are said to be severe,260° C./1 minute), it is appropriate to add a crosslinking agent.

To suggest a thermally activated adhesive whereby it is possible to forma adhesive film whose surface practically does nbt have adhesiveproperties.

Solution measures

A thermally activated adhesive composition material, characterized bythe fact that it is a thermally activated adhesive composition materialthat is formed from an adhesive polymer and a polyester, where the abovedescribed adhesive polymer material is formed so that it contains apolymer that has a hydroxyl radical and a phenyl radical in itsmolecule.

What is claimed is:
 1. A thermally activated adhesive compositioncomprising adhesive polymer and polyester, wherein the adhesive polymercomprises a polymer polymerised from (A) phenoxy alkyl acrylate; (B)hydroxy-phenoxy alkyl acrylate; and optionally (C) (meth)acrylic acidalkyl ester.
 2. The thermally activated adhesive composition accordingto claim 1, wherein the polyester is polycaprolactone.
 3. An adhesive inthe form of a film comprising the thermally activated adhesivecomposition according to claim 1.